What is Lady Macbeth is writing and why can't the gentlewoman repeat her words?
"Since his Majesty went into the field, I have
seen her rise from her bed, throw her nightgown upon her,
unlock her closet, take forth paper, fold it, write upon't, read
it, afterwards seal it, and again return to bed; yet all this
while in a most fast sleep" (V.i.3-7)
Shakespeare uses Act V, scene one, to reveal Lady Macbeth's quick deterioration under the enormous strain of guilt through the eyes of the gentlewoman. According to her, Lady Macbeth has been sleep-walking for many nights. During her sleep-walking, the Lady has been writing something down on a piece of paper and she has also been talking in her sleep as well. Now, the audience never learns from the Gentlewoman or Lady Macbeth what was on those pieces of paper; the paper could have been a note to Macbeth or a signed confession of guilt, and the Gentlewoman refuses to tell the doctor what her Lady has been saying.
"Neither to you nor any one, having no witness
to confirm my speech" (V.i.15).
The Gentlewoman feels that Lady Macbeth is not in her right mind; she has probably overheard the Lady say some pretty incriminating things during those long nights. Her silence on the matter is more than likely an act of conscience; the Gentlewoman does not wish to repeat any of Lady Macbeth's mad mutterings, because she feels sorry for her deteriorated mental condition.